A resistance gene against the potato blight, Phytophthora infestans, which is infamous for triggering the Irish famine of the 1840s and is still a major threat today, is reported online this week in Nature Plants. This gene has been isolated from a South American wild relative of cultivated potatoes.

Vivianne Vleeshouwers and colleagues searched the germplasm of wild members of the Solanum family (which includes the potato) looking for genes that responded to an elicitin (a conserved protein with an important biological function, making it less likely that the pathogen will evolve to evade resistance) from the blight pathogen. After a 10-year search, they found one such elicitin response gene, ELR, which encodes a receptor-like protein in the South American plant Solanum microdontum. Plants contain many of these cell surface receptors, which constitute the first line of immune defence and operate like an array of radar antennas, each one tuned to a different but conserved feature of the invading pathogens.

The authors found that the simultaneous presence of ELR and elicitin kills the cells around the site of infection, a powerful plant defence mechanism that restricts the progress of the pathogen. When they transferred the ELR gene into a cultivated potato strain, it made it more resistant to several strains of blight, opening new strategies for breeding a broad and durable resistance in potato varieties, increasing food security and reducing the use of fungicides.